combat communication

[Hayling]

You guys have peaked my interest in these Direct Talk phones. I've got a few newbie questions.

1) I'm assuming you don't need any phone contract in order for Direct Talk to work? You just buy the old phone, put a SIM card in it, and Direct Talk works?

2) These aren't just 2-way communication devices, right? Any phone on the same channel can communicate with all other phones on the same channel?

3) Sounds like the range ability is better than a standard FRS/GMRS radio. Is this correct?

Thanks!

[Cosantoir]

You guys have peaked my interest in these Direct Talk phones. I've got a few newbie questions.

1) I'm assuming you don't need any phone contract in order for Direct Talk to work? You just buy the old phone, put a SIM card in it, and Direct Talk works?

2) These aren't just 2-way communication devices, right? Any phone on the same channel can communicate with all other phones on the same channel?

3) Sounds like the range ability is better than a standard FRS/GMRS radio. Is this correct?

Thanks!

1) Correct. Nextel "locks" their handsets, so you need to use a Nextel (or Boost?) SIM card, otherwise the handset will go into "subsidy lock." But it doesn't need to be an active SIM card or even the correct size SIM card for the phone. Without a SIM in the phone it will not complete the power-up process. You can find used 32k Nextel SIM cards for 2 for $3 on Ebay and these will allow the phone to complete power-up, plus allow storing phone numbers for "private call" usage. Insert SIM, power phone up and switch to Direct Talk via Menu, More and Direct Talk.

2) Correct. There are 10 "channels." There are also 15 "privacy codes" but they don't really add any security, there is a "Receive All" option that will allow reception of all codes on a channel. You can also make a "private call" to a particular handset using the phone number assigned to that handset. The phone number can be changed from the handset "My Info" menu though, and you can even assign the same phone number to multiple handsets, in effect creating your own private channel that is not visible to other handsets, even in "Receive All" mode.

3) I haven't compared these side-by-side with my old cheap Motorola FRS radios, but under even ideal conditions I was lucky to get over 2 miles range on those. The Nextels have done far better than that with the stock antennas, and there are two options for upgrading the antennas. There is a "rubber ducky" antenna made by Motorola for the i325 that will fit many other Nextel phones, part number is NNTN5539, they cost about $7 on Ebay. There's also a port on the back of the phone for an external antenna, and adapter cables are about $8 on Ebay. A suitable 900 MHz antenna will be about another $20-25 and would make sense for an operations center or a vehicle.

[RadioShooter]

I have heard that a iden phone purchased from a Boost dealer may not work on Direct Talk due to hardware/software lockouts. However, I bought two Boost starter kits and put the sims in the former Nextel I355's and put them on a basic plan. The Direct Talk still works on them, so it is an option.

RS

[RadioShooter]

Cosantoir,

I found out that the i355's can use the i325's fixed antenna. Do you have these on your radios? Seems like it would be better for tactical use than the pull out one. I have kept my eye's out for some headsets for them too. Also, are you familiar with the in-house repeater for Direct Connect? Could that be made into something interesting if only for the 902-928 ham band?

RS

[Rockfish Dave]

We have these secure coms:

http://www.trisquare.us/exrs.htm

[RadioShooter]

What did you pay for the TriSquare radios? Our local Best Buy store has them in a two pack for about $89.00, so that is why I went with the i355's. The exrs is advertized at 1 watt, so is about double the power of the Nextels. I was concerned that the TriSquare might not hold up to rough use. If you have used them, let us know what you think. Too bad they don't make a ruggedized version with a longer antenna.

RS

[Radio guy]

You can get Trisquare TSX100s for $25 new on Ebay. I've used them and they seem fairly rugged, the range is a bit farther than FRS radios and the receive audio is much better than any FRS radio I have seen. There is a particular round SMA chassis connector that looks like it will fit in the snap in groove that currently holds the antenna outer sleeve. The stock antenna is a 1/4 wave whip inside the sleeve. If this works out there are plenty of cheap 800MHz 1w in 10w or more out amplifiers that should be tunable to the 902-928MHz range for these radios.
Radio Guy

What did you pay for the TriSquare radios? Our local Best Buy store has them in a two pack for about $89.00, so that is why I went with the i355's. The exrs is advertized at 1 watt, so is about double the power of the Nextels. I was concerned that the TriSquare might not hold up to rough use. If you have used them, let us know what you think. Too bad they don't make a ruggedized version with a longer antenna.

RS

[kir]

On the issue of security I am reminded of the "battle language" and "hunting language" alluded to in Frank Herbert's "Dune". Which brings to mind the use of Navajo in WW2.

Much like preshared key encryption, both transmitter and receiver would need to have worked out their "language" before hand.

You wouldn't need to be able to translate Shakespeare into your "language", just have useful words predetermined. Key concepts like "friend", "enemy", "supplies" as well as things like directions, distance, time and units to go with these concepts. As well as simple actions, "stop", "go", "fire", "help".

For those with more interest in the underlying linguistic mechanics of what purpose built languages could entail see Sapir-Whorf hypothesis.

Anyway, just a silly idea from a ham who reads too much Dune.

[Cosantoir]

I have heard that a iden phone purchased from a Boost dealer may not work on Direct Talk due to hardware/software lockouts. However, I bought two Boost starter kits and put the sims in the former Nextel I355's and put them on a basic plan. The Direct Talk still works on them, so it is an option.

RS

Handsets sold by Boost have the Direct Talk function locked out via software. I think that's also the case with SouthernLINC iDEN phones. SouthernLINC will enable DT over the air for a $20 or $25 fee, supposedly, but that would require that the handset be active on SouthernLINC's network at the time. I don't know if SouthernLINC handsets are set to go into subsidy lock if another carrier's SIM is inserted.

People report being able to enable DT on Boost handsets via minor changes in the codeplug. I've never tried it, since I was able to find cheap Nextel handsets.

Even though Boost is part of Sprint-Nextel, Boost handsets will often go into subsidy lock if a Nextel SIM card is inserted. Boost SIMs in Nextel handsets don't seem to cause any problems. Direct Talk will still be available on those handsets even if the Boost SIMs are no longer active. Another option is buying a used Nextel SIM off Ebay. The SIM can be inactive, or even on the "negative file" (SIMs reported lost, stolen or replaced through a handset insurance claim), and even though the i355 is intended to use a 128k SIM, it will work fine with even a 32k SIM. You can find those on Ebay for next to nothing.

[LowKey]

There's a decent hand signal dictionary floating around the interwebs, pictures of a guy in a black balaclava and an MP5. I'm sure somebody here knows where to link to it.

ETA: http://www.lefande.com/hands.html

Can't post the image itself for some reason.

Chef, your hand signals are out of date....here's the updated one in use by most SWAT/LEO these days.Updated Swat/LEO Hand Signals
I wouldn't want anyone to get hurt because of outdated info. Be more careful next time.

[Cosantoir]

Cosantoir,

I found out that the i355's can use the i325's fixed antenna. Do you have these on your radios? Seems like it would be better for tactical use than the pull out one. I have kept my eye's out for some headsets for them too. Also, are you familiar with the in-house repeater for Direct Connect? Could that be made into something interesting if only for the 902-928 ham band?

RS

That is correct. The fixed antenna from the i325 can be used on the i355. Also on the i315, and possibly on the i365? Motorola part number is NNTN5539. There are a couple of places that have these at good prices:

https://www.unlimitedcellular.com/p-291 ... n5539.aspx

http://www.radioaccessories.com/product ... 000749.htm

I've dealt with both outfits and had positive experiences.

The fixed antenna seems to be a good bit more rugged than the stock extending unit, and it has noticeably better performance. I've made contacts at slightly over 9 miles, hilltop to hilltop, with the fixed antenna. About 6 or 7 was the maximum with the stock antenna extended, and far less with it collapsed.

There's also a socket for an external antenna cable. This would not be a bad idea if using a DT handset in a vehicle, or at a fixed OP or operations center.

Headsets are a useful addition, but it can be difficult to find a headset that will work with the iDEN phones. At least at reasonable prices and rugged enough to hold up to field use. Motorola uses a proprietary connector (actually, two of them) for these phones. The connectors have 4 conductors (compared to the 3 of most cellphones) with the fourth being for the PTT button. There are actually two designs that have been used. The first resembles the standard 2.5mm connector used for many cellular headsets, but has a circular metal conductor, concentric to the shaft of the plug, that provides the fourth conductor for the PTT function. The other variation simply added a fourth conductor to the shaft of the plug.

I haven't found a source for either of these connectors yet, but I'm sure there's more than one out there. It should be fairly easy to fabricate an adapter to use affordable and reasonably rugged off-the-shelf FRS or cycling-intercom headsets, with an added PTT button.

The pin-out for the second pattern of iDEN headset connectors can be found at http://pinouts.ru/CellularPhones-A-N/mo ... nout.shtml

The Direct Connect repeaters would not work. They operate in the 800 MHz band, and do not have a frequency-hopping capability. But it would probably not be too hard to build a repeater out of two DT-capable phones and a retransmit cable. The data and charging cable used on most iDEN phones appears to include audio and PTT lines. The pin-out can be found at http://www.blogcadre.com/node/1295

I've ordered a couple of cheap iDEN/USB data cables to break down for the connectors. Once they arrive I will do some experimenting. A simple repeater that could be placed on a hill or tall building would be extremely useful

[RadioShooter]

Interesting and along the line of what I was thinking about doing. I would like to only carry one radio with me and had an idea about interfacing a Nextel with a VHF HT to sort of cross band. The feature is available in some of the incident command radio patches: that is Iden to VHF/UHF. They are too expensive for me to purchase. I have a control board that I built years ago to allow frequency selective cross band from UHF to VHF using different CTCSS tones to switch audio and channels. The only sticking point is where do you get the PTT from the Iden to the VHF? Hopefully it is on the base data plug. What could you do if it is not there?

Interesting thread here.

RS

[Samurai-5]

In the following order:

-Land Line
-Cell Phone
-Base Station (Yeasu 7800)

Then the Combat Stuff:
-2M portable (Yeasu VX-R)
-Whistle
-Voice
-Pyrotechnics
-Hand & Arm Signals

As has been stated before, NEVER rely on electronics.

[RadioShooter]

Never rely on electronics? Seems like a lot of guys are using holo sights and night vision optics on their home defense weapons. (Not me).

Well I put the fixed antennas on the i355's and it does seem to extend the range somewhat. My son and I used them at the Blade Show in Atlanta last Saturday and they worked just fine with no interference. At home, the terrain limits comms to about 1/3 of a mile. The external antennas do generate interest from the general public since it no longer looks like a cell phone. Other than the problem of battery charging, I think I will get my money's worth from these. For Tac use, I may pick up another Icom F30GT to have a matched set. The longer range on the 2 meter band could be decisive. No reason why you couldn't use both. Maybe this Friday I will get a chance to setup the 2 meter wide split repeater and see what it can do for a range extender.

RS

[toecutter]

Some interesting topics have been brought up on this thread since I last checked. The idea of using PtP on old nextel phones is an interesting one, I will have to investigate that further.

While I don't think Amateur radio should be ignored as some have suggested in favor of land mobile radios (MT Sabre and others), it seems being mindful of your transmit power and direction of transmission (using a Yagi to communicate back to base) is an important aspect of operational security, just as much as the language you use on the radio is important. Since some people have brough up using different modes (P25, DSTAR, etc) what about using other digital modes with encryption? RTTY, and simply encrypting the message before sending.

High bandwidth, fast communication transmission modes (9600b packet, and others) combined with basic encryption (vegenere, ceasar, book etc) working in concert with directional antennas can limit the exposure of your information as well as any possibility of DF giving your position away.

Personally, I'm not a huge fan of the sabre radios, and important aspect to remember about these is if the battery is removed while the radio is in the "on" position, even if it has a dead battery will dump the crypto keys, and likely the rest of the memory. While this is designed as a security feature, to allow you to dump the crypto in case of capture, it has the disadvantage of dumping your crypto keys if you are not mindful of what you are doing.

It seems 90% of the security issues that occur with regular radio usage are directly due to how they are used. So being mindful of how you use a radio will go a long way to make sure radio communications stay secure.

As far as what radio to use, avoid GMRS/FRS, or any other consumer grade COTS radios that are commonly availible, a survey of what walmart has in the electronics department for under $40 per radio is probably a good idea of what to avoid. HAM radios when modified are capable of both talking to GMRS/FRS radios, as well as listening to them. Thus far it seems Icom, Yaesu and Kenwood have all done an amazing job of making multiband FM handhelds, when the TX/RX is opened up on these an amazing frequency range can be covered.

Another important aspect that bears mention is the use of AA battery packs. Yes, AA packs full of rechargables are a great option, this gets around the issue of packs wearing out and not being able to take a charge, they can simply be refilled with fresh AA rechargables. However, for your "backup stash" of AA's for emergency use, spend the extra cash and get the lithium cells, these have a lot more power when you need it, and have shelf-lives between 10 and 15 years. Energizer Ultra-Lithium Cells are supposed to retain 90% charge after 15years. The addition of an external 12V AA battery charger (these are availible at walmart, and usually hold 2-4 cells, fit easily in a pocket or backpack) should be considered a neccessity.

[RadioShooter]

I just checked the battery drawer and there are about 60 AA alkaline batteries in there. We use them on a regular basis and replenish with the 24 packs. I just noticed that my public safety Icom speaker mics don't have a jack for an earbud. Both of the speaker mics for the Icom U82's have the jacks. I can't complain since I got them for less than half price on the web. I guess they could be added ( a switched jack and a resistor). In a TEOTWAWKI situation, radio power might cease to be important after a year. For a SHTF situation that rolls on for several months, I need to plan a little more ahead. I think you are correct about avoiding any commonly available two way stuff for your group's comm system although listening around on the FRS/GMRS might not hurt.

There are a couple of banks in my non-keypad programmable radios loaded with amateur radio freqs for my groups comms.

RS

[WoG]

Well, if they can hear you, chances are they can see you, and then chances are they can shoot you.

Anytime I've been out in the woods during the day, I generally see something moving long before I hear it.

At night you hear -everything- so unless you're fighting ninjas you should hear them coming. So unless you're gunna buy throat mics and all...

I'm not a combat vet, but if they can hear you and see you - I think you're doing it wrong.

[toecutter]

More importantly, if they can hear you, they can call a mortar strike on the position they think you are at. Also, if you can hear them, you may be close enough to stumble into any booby traps they set.

[Slugg]

More importantly, if they can hear you, they can call a mortar strike on the position they think you are at. Also, if you can hear them, you may be close enough to stumble into any booby traps they set.

I kinda think artillery or mortar fire are out of the question currently. The only thing I could imagine is the old pipe bomb strapped onto a model rocket. But that is not accurate nor reliable from my expirience.. Boobytraps are still an issue +1 on that. Yes, backups like hand motions the hawk noise and colored smoke bombs are great ideas.

[toecutter]

I kinda think artillery or mortar fire are out of the question currently. The only thing I could imagine is the old pipe bomb strapped onto a model rocket. But that is not accurate nor reliable from my expirience.. Boobytraps are still an issue +1 on that. Yes, backups like hand motions the hawk noise and colored smoke bombs are great ideas.

There is a lot of heavy weaponry stationed all over the country, and in some cases not well guarded. I know the national guard armories near me, one is full of tow missles, the other one is a artillery brigade, and has several paladin's parked out front. Since mortars are usually considered a "crew served" weapon rather than something specialized like artillery cannons, it's likely they would be more ubiquitous if things fell apart. However, god only knows if your adversary would be able to employ them to any effect. As we have seen with the hajis over in the sandbox, the target needs to be about the size of the green zone, and even then it's still not a sure thing.

[Stab74]

Wow I love you guys. I was about to buy 2 cobra gmrs radios on sale but decided to check here first. Glad I did! Just ordered two i355's and two 32k sim cards on ebay and ordered 2 of the fixed antennas from one of the sites listed above. I have a buddy that lives .89 miles from me according to google earth that I would like to maintain secure comms with in an emergency. We both live downtown though so not sure if this will work. Will experiment with going to the top floor of my apartment building. If that doesnt work I'll try from the top floor of the high rise apartment building across the street. Will update when I get a chance to experiment.

[Hayling]

Wow I love you guys. I was about to buy 2 cobra gmrs radios on sale but decided to check here first. Glad I did! Just ordered two i355's and two 32k sim cards on ebay and ordered 2 of the fixed antennas from one of the sites listed above. I have a buddy that lives .89 miles from me according to google earth that I would like to maintain secure comms with in an emergency. We both live downtown though so not sure if this will work. Will experiment with going to the top floor of my apartment building. If that doesnt work I'll try from the top floor of the high rise apartment building across the street. Will update when I get a chance to experiment.

Excellent. Definitely let us know how it goes! I'm still wanting to pick up a set of these i355's.

[crypto]

What kind of power do these Nextel phones need? I'd be scared of something that was bound to a proprietary Li-Ion battery pack, because in 3-4 years when that battery pack is useless, getting a replacement may be a hassle.

Even sitting on a shelf in the shrink-wrap batteries that are brand new now will be useless in the future, as a result of the way Li-Ion bats permanently degrade over time. Getting newly-manufactured batteries for an old phone in the future will be problematic.

And thats just in todays battery market, let alone the PAW.

[RadioShooter]

The radios have 0.6 watt output, the same as the cell phone half of the unit. Yeah, the batteries may be a problem eventually but versions of them are used in many different models of Nextels. The i355's are cheap, reasonable secure if used correctly, license free, and much better constructed than the usual OTC FRS stuff. You can put a Boost pay as you go sim in them and get some real emergency use out of them. That is what I am doing.

I will be out of toilet paper long before the batteries die anyway. Why live if you can't wipe in confort.

RS